Photorespiration and RuBisCO in C3 Plants — NEET Biology
✅ Asked in NEET 2024In C₃ plants some O₂ does bind to RuBisCO, and hence CO₂ fixation is decreased. Here the RuBP instead of being converted to 2 molecules of PGA binds with O₂ to form one molecule of phosphoglycerate and phosphoglycolate (2 Carbon) in a pathway called photorespiration. In the photorespiratory pathway, there is neither synthesis of sugars, nor of ATP. Rather it results in the release of CO₂ with the utilisation of ATP. In the photorespiratory pathway there is no synthesis of ATP or NADPH. The biological function of photorespiration is not known yet.
NTA tests your understanding of photorespiration—when O₂ binds to RuBisCO instead of CO₂ in C3 plants, reducing carbon fixation. The key trap: students confuse photorespiration with photosynthesis or think it produces ATP and sugars like the Calvin cycle does. Remember, photorespiration consumes ATP and releases CO₂ without producing sugars or ATP—it's essentially wasteful. NEET asks why this happens and its outcomes; the biological function remains unknown, making it a critical concept for C3 vs C4 plant efficiency questions.
This paragraph was tested 2 times in NEET.
(NEET 2024) Given below are two statements: Statement I: In C₃ plants, some O₂ binds to RuBisCO, hence CO₂ fixation is decreased. Statement II: In C₄ plants, mesophyll cells show very little photorespiration while bundle sheath cells do not show photorespiration. In the light of the above statements, choose the correct answer:
The oxygenation activity of RuBisCO enzyme in photorespiration leads to the formation of: (NEET 2020)
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